The present invention relates to a separator of the type having a plurality of parallel rows of interleaved discs rotating in the same direction whereby material fed onto the tops of the discs will be passed along from one row to the next, the finer material dropping through the spaces between adjacent discs, the coarser material being carried along on top of the discs whereby separation of fine and coarse material may be obtained. A problem exists with such separators in maintaining clearance between discs when spacing is close. The present invention provides means for accurately spacing the dics of one row relative to those of an adjacent row and for rapidly and easily changing the spacing of the discs in the event it is desired to obtain a different degree of separation.